In the past, people with any significant degree of astigmatism were excluded from laser eye surgery, leaving only glasses or contact lenses as options to correct astigmatism. However, with the progress of laser eye surgery technology, it is now possible to access LASIK for astigmatism, meaning more people can now be free from their glasses and contacts. Keep reading to find out how we can use LASIK eye surgery to correct astigmatism.
All About Astigmatism
Astigmatism is a type of refractive error. It can occur at the same time as long-sightedness (hyperopia) and short-sightedness (myopia). Refractive errors occur when an eye’s focusing system is not perfectly matched to the length of the eyeball, so light is not focused sharply on the retina. In order to perceive clear vision, we need light to come to a pinpoint focus on the sensory retina at the back of the eye. In hyperopia, light comes to a focus behind the retina; in myopia, light focuses too early and falls before the retina. In astigmatism, light is actually focused at two separate points, depending on which direction the light ray enters the eye. One or neither of these points may be focused on the retina, leading to blurry vision
Astigmatism is caused by an uneven curvature of certain structures of the eye, which results in light being bent, or refracted, to different degrees. A popular analogy is to compare a soccer ball to an AFL football. While a soccer ball has the same degree of curvature no matter which direction you follow around the ball, an AFL football has a steeper curve around its middle and a flatter curve from tip to tip. The majority of astigmatism cases are caused by the cornea (corneal astigmatism), which is the very front surface of the eye. However, astigmatism may also arise from the lens inside the eye (lenticular astigmatism). It is possible for LASIK eye surgery to address both.
Symptoms of astigmatism can include:
- A flaring or starburst pattern of lights, such as car headlights at night
- Difficulty with night vision due to glare
- The sensation of ghosting or shadowing of images
- Blurry vision at all distances
- Headaches or eyestrain when reading
An optometrist can easily diagnose your type of refractive error with a routine eye test and correct astigmatism with glasses or contact lenses. Patients who are interested in pursuing laser eye surgery, whether PRK, SMILE, or LASIK eye surgery, will be referred to an eye specialist. There are also other options to surgically correct for astigmatism which don’t fall under the category of laser eye surgery, such as refractive lens exchange.
How Does LASIK for Astigmatism Work?
How is LASIK eye surgery used to correct astigmatism? LASIK for astigmatism works much the same as applying LASIK eye surgery to any other type of refractive error. As with all types of refractive laser eye surgery techniques, LASIK focuses on modifying the shape of the cornea to change the way light bends through this surface. The aim is to redirect light to focus where we need it to provide sharp vision – right on the retina.
On the day of your laser eye surgery, your eye will be prepared with a topical anaesthetic to make the procedure more comfortable for you. Once your eye is well numbed, the surgeon will create a flap out of the cornea. This can be performed either using a manual tool known as a microkeratome or with a femtosecond laser.
Both techniques are considered safe and effective. When the flap has been created, it is then gently placed to the side of the eye, though remains attached. This allows the excimer laser to be applied to the deeper corneal layers in a process called photoablation. Photoablation is the vaporisation of small selected areas of corneal tissue in order to change its shape.
The excimer laser is precisely guided by a computer algorithm. During your initial consultations, you would have had biometric measurements are taken, which include assessing the shape of your cornea, measurements of corneal astigmatism versus lenticular astigmatism, and your exact refractive error. It’s these advancements in technology that have made LASIK for astigmatism possible.
Am I Eligible for LASIK?
Regardless of whether you have high astigmatism or perfectly soccer-ball-shaped corneas, there are a few criteria to ensure the LASIK procedure is safe and effective for you:
- Minimum corneal thickness. Because laser eye surgery involves the removal of corneal tissue, it’s important to ensure you have enough to begin with. The exact degree of corneal thickness required can be influenced by your prescription, as the higher the script, the more tissue needs to be photoablation. People with thin corneas may be unsuitable for LASIK but still eligible for another procedure, such as PRK.
- Maximum prescription. As a general guideline, LASIK is able to correct very high degrees of myopia, around -11.00D, high hyperopia up to +5.00D, and high astigmatism up to -5.00D. However, the higher the prescription, the higher the risk of side effects after surgery, such as night-time glare.
- Your vision isn’t limited by other eye diseases. Laser eye surgery won’t restore any vision lost from other eye or vision conditions such as the lazy eye (amblyopia) and retinal damage.
- You’re under the age of 55. Different surgeons may have a slightly different age cut-off, however, the reasoning is based around the age-related decline of your near vision, which would not be improved with LASIK. In these cases, you may be guided to another procedure such as refractive lens exchange.
To see if you’re eligible for LASIK, speak to your eye care professional.
Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.
References
Can laser eye surgery fix astigmatism?
https://visioneyeinstitute.com.au/eyematters/can-laser-eye-surgery-fix-astigmatism/
Does my eyeglass prescription qualify for LASIK?
https://www.allaboutvision.com/visionsurgery/faq-prescription.htm
LASIK eye surgery is a popular form of refractive surgery, a category of eye procedures designed to surgically correct the Read more
LASIK eye surgery is a type of refractive surgery. Refractive surgeries are a group of procedures that surgically correct the Read more
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